Vapor compression refrigerant system with secondary modulating heat transfer

ABSTRACT

A vapor compression refrigeration system having an air dehumidifying system and a heat transfer system. The dehumidifying system has a refrigerant circuit and an air circulating system transporting air from an enclosed space at least partly through the refrigerant circuit and back to the enclosed space. The refrigerant circuit carries a phase change refrigerant which picks up heat from the air passing through the air circulating system. The heat transfer system carries a fluid that will not freeze below the ambient temperature. A heat exchanger connects the refrigerant circuit to the heat transfer system to pass heat from the phase change refrigerant in the refrigerant circuit to the fluid in the heat transfer system. At least one heat removal unit in the heat transfer system to remove heat from the fluid.

BACKGROUND OF THE INVENTION Field of the Invention

This invention is directed toward a vapor compression refrigerant system with secondary, modulating, heat transfer used to control the environment in an enclosed space.

Background Art

The invention is particularly directed toward a vapor compression refrigerant system to control the environment in an indoor swimming pool. The refrigerant system can control properties of the air in the indoor swimming pool and the temperature of the water in the swimming pool. It is known to control the quality of the air in an indoor swimming pool using a refrigerant circuit circulating a refrigerant. The refrigerant normally used is a phase change refrigerant. It is also known to use the refrigerant to heat the pool water.

The use of vapor compression refrigerant systems using phase change refrigerants is costly. The refrigerant is itself costly. The piping system required is costly and maintenance of the piping system is intensive, adding to the cost. There is the possibility that the refrigerant, or oil from a compressor used with the refrigerant, can leak into the swimming pool water, contaminating the water. The cost further increases due to construction and testing normally required at the site. Control of the system is difficult due to the off-on controls employed.

SUMMARY OF THE INVENTION

It is the purpose of the present invention to provide a vapor compression, refrigerant system to control the environment in an enclosed space, such as an indoor swimming pool, which system is cheaper to build, cheaper to maintain, and cheaper to operate than known systems. It is a further purpose of the present invention to provide a vapor compression, refrigerant system which provides better control of the operation of the system and thus better control of the properties of the air in the system and the temperature of the water in the system.

The vapor compression refrigerant system of the present invention employs a simple air dehumidifying system to treat the air from an enclosed space and a heat transfer system to eliminate heat taken out of the air by the air dehumidifying system. The air dehumidifying system employs a phase change refrigerant and is connected to the heat transfer system by a vapor/fluid heat exchanger. The heat transfer system employs a fluid with a low freezing temperature, such as glycol. The heat transfer system has heat removal means to remove heat from the system, Proportional control valves are provided in the heat transfer system to direct precise amounts of the heated fluid to selected ones of the heat removal means as needed. At least one of the heat removal means can provide heat for use in the enclosed space.

The present invention minimizes the use of costly phase change refrigerant in the system. The system can result in up to 90% less refrigerant being used in the system. With substantially less refrigerant being used, the piping for the system is simplified. The system can be more easily assembled and tested in a factory before shipment. The system allows the treatment of pool water without the risk of contaminating the water with refrigerant or oil.

DESCRIPTION OF THE DRAWING FIG. 1

FIG. 1 shows the layout of the system.

DESCRIPTION OF PREFERRED EMBODIMENT

The vapor compression refrigerant system 1 shown in FIG. 1 has a dehumidifying system 3, for treating air from an enclosed space 5 where evaporation occurs, such as an indoor swimming pool. The vapor compression refrigerant system 1 also has a heat transfer system 7 for removing heat from the dehumidifying system 3.

The dehumidifying system 3 has an air circulating system 9 for transporting air from the indoor swimming pool 5 through a pool air inlet duct 11, into one end 13 of a main air duct 15 and passing through the main air duct 15 to its other end 17 and back to the swimming pool 5 via a pool air outlet duct 19. A fan 21 at the other end 17 of the main air duct 13 circulates the air through the air circulating system 9. The air circulating system 9 includes an outside air inlet duct 23 located between the pool air inlet and outlet ducts 11, 19 for adding outside air to the circulating air in the main air duct 15 if required.

The dehumidifying system 3 has a refrigerant circuit 27 comprising a compressor 29, a heat exchanger 31, an expansion valve 33, and an evaporator 35 connected in series in a loop with a refrigerant line 37. The evaporator 35 and the expansion valve 33 are located in the main air duct 13 of the air circulating system 9, between the outside air inlet duct 23 and the pool air inlet duct 11, to condition the air passing through the main air duct 13. The refrigerant circuit 27 carries a phase change refrigerant. The evaporator 35 is in the path of the returning pool air in the main air duct 13 that has entered from the pool air inlet duct 11. The evaporator 35 can remove heat and can condense moisture from the return pool air to condition the air.

The vapor compression refrigerant system 1 includes a heat transfer system 7 operating with a normally non-freezing fluid such as glycol. The fluid used would not freeze below the ambient temperature. The heat transfer system 7 is connected to the refrigerant circuit 27 with the heat exchanger 31. The heat exchanger 31 is a refrigerant/fluid heat exchanger. The heat transfer system 7 picks up heat from the refrigerant circuit 27 in the heat exchanger 31.

The heat transfer system 7 has a feed line 41 leading from the heat exchanger 31 to a heat removal unit 43, such as an outside air preheat coil 51, if needed, which can be mounted in the outside air duct 23. The preheat coil 51 uses the heated fluid to selectively heat outside air entering the main air duct 17 when required. The heat transfer system 7 includes a return line 53 returning the fluid from the preheat coil 51 to the heat exchanger 31. A valve 55 in the return line 53 controls the flow of the fluid through the preheat coil 51. A pump 57 is provided in the return line 53, before the heat exchanger 31, to circulate the fluid through the heat transfer system 7.

The heat transfer system 7 can have a second heat removal unit 43 a, if needed, in the form of a reheat coil 59 which can be mounted in parallel with the preheat coil 51 between the feed line 41 and the return line 53 of the heat transfer system 7. A branch feed line 41 a connects feed line 41 to the reheat coil 59 and a branch return line 53 a connects the reheat coil 59 to the return line 53. The reheat coil 59 is mounted in the main air duct 17 just past where the outside air duct 23 joins the main air duct 17 and is used to selectively reheat the return air from the pool area and/or the added outside air if needed.

The heat transfer system 7 can have a third heat removal unit 43 b in the form of a fluid cooler 65 mounted outside the main air duct 15 of the air circulating system 3. The fluid cooler 65 is connected between the feed and return lines 41, 53 a with branch lines 41 b, 53 b. The fluid cooler 65 acts as a heat exchanger between the heated fluid and outside air drawn through the cooler. The fluid cooler 65 is connected to the return branch line 53 b with a first three way modulating mixing valve 67. The mixing valve 67 can be used to proportion flow of the fluid between the fluid cooler 65 and the reheat coil 59 if needed.

The fluid cooler 65 can be replaced with: a fluid to fluid heat exchanger to reject heat to an external heat rejection system. The fluid to fluid heat exchanger can also be used for a heat pump heating mode whenever the compressor is not running during winter, absorbing heat from the external loop.

A fourth heat removal means 43 c in the form of a pool water heater 69 can be used in the heat transfer system 7. The pool water heater 69 is connected between the feed and return lines 41, 53 of the heat transfer circuit 7 with branch lines 41 c, 53 c just after the branch return line 53 b and before the pump 57. Branch return line 53 c is connected to the return line 53 with a second three way modulating mixing valve 71. The second mixing valve 71 can be used to proportion flow of the fluid between the pool water heater 69 and the fluid cooler 65 and/or the reheat coil 59 to maintain the refrigerant head pressure set point in the refrigerant circuit 27.

While the system 1 has been described with four different heat removal means it can be employed with any single one of the heat removal means or with any other combination thereof. A preferred combination of the heat removal means would involve using the reheat coil 59, the fluid cooler 65 and the pool water heater 69 to dissipate the heat extracted from the refrigerant circuit 27 of the dehumidifying system 3. The two modulating mixing valves 67, 71 would direct the required amount of heat to the reheat coil and the pool water heater. Any excess heat would be disposed of through the fluid cooler, if required.

The system 1 allows infinite control of the air temperature and humidity and of the water temperature. Surges of power and temperature due to the start and stop of the compressor 29 and the pump 57 in the refrigerant circuit 27 and the normal fluctuations of temperature in the refrigerant in the refrigerant circuit are eliminated by the use of the modulating heat transfer circuit 7. 

1. A vapor compression refrigeration system having an air dehumidifying system and a heat transfer system; the dehumidifying system has a refrigerant circuit and an air circulating system transporting air from an enclosed space at least partly through the refrigerant circuit and back to the enclosed space; the refrigerant circuit carrying a phase change refrigerant which picks up heat from the air passing through the air circulating system; the heat transfer system carrying a fluid that will not freeze below the ambient temperature; a heat exchanger connecting the refrigerant circuit to the heat transfer system to pass heat from the phase change refrigerant in the refrigerant circuit to the fluid in the heat transfer system; at least one heat removal unit in the heat transfer system to remove heat from the fluid.
 2. A vapor compression refrigeration system as claimed in claim 1 wherein the heat removal unit is a preheat coil, the preheat coil located in the air circulating system for preheating air added to the circulating air; and a valve in the heat transfer system for controlling circulation of the fluid to the preheat coil.
 3. A vapor compression refrigeration system as claimed in claim 1 wherein the heat removal unit comprises a reheat coil; the reheat coil located in the air circulation system for reheating air that has passed through the refrigerant circuit.
 4. A vapor compression refrigeration system as claimed in claim 1 wherein the heat removal unit comprises a fluid cooler adjacent the air circulating system for transferring heat from the fluid to outside air passing through the fluid cooler.
 5. A vapor compression refrigeration system as claimed in claim 1 wherein the enclosed space is an indoor swimming pool and the heat removal unit comprises a pool water heater.
 6. A vapor compression refrigeration system as claimed in claim 4 including a second heat removal unit in the heat transfer system and a three way modulating mixing valve selectively controlling fluid flow between the fluid cooler and the second heat removal unit.
 7. A vapor compression refrigeration system as claimed in claim 5 including a second heat removal unit in the heat transfer system and a three way modulating mixing valve selectively controlling fluid flow between the pool water heater and second heat removal unit.
 8. A vapor compression refrigeration system as claimed in claim 6 including a third heat removal unit in the heat transfer system and a second three way modulating mixing valve selectively controlling, along with the first three way modulating mixing valve, fluid flow between the fluid cooler and the second and third heat removal units.
 9. A vapor compression refrigeration system as claimed in claim 7 including a third heat removal unit in the heat transfer unit and a second three way modulating mixing valve selectively controlling, along with the first three way modulating mixing valve, fluid flow between the pool water heater and the second and third heat removal units. 